Motor vehicle traffic congestion occurs in cities and towns in the United States and in other countries around the world. Many automobiles and other motor vehicles have internal combustion engines that burn fuel (whether gasoline or diesel fuel) even when the vehicles are sitting idle in traffic. The effluent from such engines pollutes the environment.
Drivers of motor vehicles often drive sub-optimal routes over public and/or private roadways on the way to their destinations. A driver also will often leave well in advance of a desired arrival time to try to ensure or increase the likelihood of arriving at the desired time, even when being guided along the roadways by a GPS (Global Positioning System) navigation device or when following driving directions from a web service such as MapQuest, Google Maps, Yahoo Maps, or Microsoft Live Maps.